Projekt Anglicky v odborných předmětech, CZ.1.07/1.3.09/04.0002 Anglicky v odborných předmětech "Support of teaching technical subjects in English“ Tutorial: Mechanic - electrician Topic: Basics of electrical engineering the 2nd. year Three-phase current Circuit breaker Prepared by: Škarka Miloš Projekt Anglicky v odborných předmětech, CZ.1.07/1.3.09/04.0002 je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky.

Circuit breaker The circuit breaker is an electric device, which during the excessive current (so called over current) (usually during overload or short-circuit) automatically disconnects electric circuit and by that protects operating personnel against possible injury caused by an electric current and protected electric device against damage.

Circuit breaker main functions Circuit breaker provides in electric circuit these basic functions: Safe automatic disconnection of the circuit in case of short-circuit Safe automatic disconnection of the circuit in case of overcurrent Manual disconnection of the circuit Manual connection of the circuit

Main parameters of circuit breakers Circuit breaker characteristic values are: Nominal voltage, which it is designed for Nominal current, which is permanently transmitted without circuit disconnection Short-circuit current, which is able to turn off (on ordinary home appliances typically 6 to 25 kiloampers). Disconnection characteristic determines the dependence of the disconnection time on the amount of overcurrent or short-circuit current.

Example of the circuit breaker design Control lever Locking mechanism Contacts Supply bolt terminal Bimetal component for overload facilities Regulation component for sensitivity setting (usually not on ordinary home circuit breakers) Electromagnetic trigger for short-circuit facilities Quenching chamber

One-pole circuit breaker Three-pole circuit breaker Connection of the pad and circuit breakers using connection battens

Color marking according to the nominal current grey   20 A blue 25 A yellow 32 A purple 40 A black 50 A white 63 A copper 0,2 A - 1,6 A black   2 A pink 4 A brown 6 A green 8 A Light green 10 A red 13 A sand

Disconnection characteristics Usage: for electric circuits protection B – with devices not causing current impacts (protection of lines) C – with devices causing current impacts (bulb groups, lines with motors) D – with devices causing high current impacts (transformers, two-pole motors)

Describe and explain: Main components of the current breaker in picture 1 Current breaker main functions Main parameters of current breakers Current breaker characteristics Picture 1

Literature http://www.bonega.cz http://www.google.cz http://cs.wikipedia.org